package keys import ( "crypto/ecdsa" "crypto/elliptic" "crypto/x509" "encoding/hex" "encoding/json" "errors" "fmt" "math/big" "github.com/btcsuite/btcd/btcec" lru "github.com/hashicorp/golang-lru" "github.com/nspcc-dev/neo-go/pkg/crypto/hash" "github.com/nspcc-dev/neo-go/pkg/encoding/address" "github.com/nspcc-dev/neo-go/pkg/io" "github.com/nspcc-dev/neo-go/pkg/util" "github.com/nspcc-dev/neo-go/pkg/vm/emit" ) // coordLen is the number of bytes in serialized X or Y coordinate. const coordLen = 32 // SignatureLen is the length of a standard signature for 256-bit EC key. const SignatureLen = 64 // PublicKeys is a list of public keys. type PublicKeys []*PublicKey var big0 = big.NewInt(0) var big3 = big.NewInt(3) // NewPublicKeysFromStrings converts an array of string-encoded P256 public keys // into an array of PublicKeys. func NewPublicKeysFromStrings(ss []string) (PublicKeys, error) { arr := make([]*PublicKey, len(ss)) for i := range ss { pubKey, err := NewPublicKeyFromString(ss[i]) if err != nil { return nil, err } arr[i] = pubKey } return PublicKeys(arr), nil } func (keys PublicKeys) Len() int { return len(keys) } func (keys PublicKeys) Swap(i, j int) { keys[i], keys[j] = keys[j], keys[i] } func (keys PublicKeys) Less(i, j int) bool { return keys[i].Cmp(keys[j]) == -1 } // DecodeBytes decodes a PublicKeys from the given slice of bytes. func (keys *PublicKeys) DecodeBytes(data []byte) error { b := io.NewBinReaderFromBuf(data) b.ReadArray(keys) return b.Err } // Bytes encodes PublicKeys to the new slice of bytes. func (keys *PublicKeys) Bytes() []byte { buf := io.NewBufBinWriter() buf.WriteArray(*keys) if buf.Err != nil { panic(buf.Err) } return buf.Bytes() } // Contains checks whether the passed param is contained in PublicKeys. func (keys PublicKeys) Contains(pKey *PublicKey) bool { for _, key := range keys { if key.Equal(pKey) { return true } } return false } // Copy returns a copy of keys. func (keys PublicKeys) Copy() PublicKeys { res := make(PublicKeys, len(keys)) copy(res, keys) return res } // Unique returns a set of public keys. func (keys PublicKeys) Unique() PublicKeys { unique := PublicKeys{} for _, publicKey := range keys { if !unique.Contains(publicKey) { unique = append(unique, publicKey) } } return unique } // PublicKey represents a public key and provides a high level // API around ecdsa.PublicKey. type PublicKey ecdsa.PublicKey // Equal returns true in case public keys are equal. func (p *PublicKey) Equal(key *PublicKey) bool { return p.X.Cmp(key.X) == 0 && p.Y.Cmp(key.Y) == 0 } // Cmp compares two keys. func (p *PublicKey) Cmp(key *PublicKey) int { xCmp := p.X.Cmp(key.X) if xCmp != 0 { return xCmp } return p.Y.Cmp(key.Y) } // NewPublicKeyFromString returns a public key created from the // given hex string. func NewPublicKeyFromString(s string) (*PublicKey, error) { b, err := hex.DecodeString(s) if err != nil { return nil, err } return NewPublicKeyFromBytes(b, elliptic.P256()) } // keycache is a simple lru cache for P256 keys that avoids Y calculation overhead // for known keys. var keycache *lru.Cache func init() { // Less than 100K, probably enough for our purposes. keycache, _ = lru.New(1024) } // NewPublicKeyFromBytes returns a public key created from b using the given EC. func NewPublicKeyFromBytes(b []byte, curve elliptic.Curve) (*PublicKey, error) { var pubKey *PublicKey cachedKey, ok := keycache.Get(string(b)) if ok { pubKey = cachedKey.(*PublicKey) if pubKey.Curve == curve { return pubKey, nil } } pubKey = new(PublicKey) pubKey.Curve = curve if err := pubKey.DecodeBytes(b); err != nil { return nil, err } keycache.Add(string(b), pubKey) return pubKey, nil } // getBytes serializes X and Y using compressed or uncompressed format. func (p *PublicKey) getBytes(compressed bool) []byte { if p.IsInfinity() { return []byte{0x00} } if compressed { return elliptic.MarshalCompressed(p.Curve, p.X, p.Y) } return elliptic.Marshal(p.Curve, p.X, p.Y) } // Bytes returns byte array representation of the public key in compressed // form (33 bytes with 0x02 or 0x03 prefix, except infinity which is always 0). func (p *PublicKey) Bytes() []byte { return p.getBytes(true) } // UncompressedBytes returns byte array representation of the public key in // uncompressed form (65 bytes with 0x04 prefix, except infinity which is // always 0). func (p *PublicKey) UncompressedBytes() []byte { return p.getBytes(false) } // NewPublicKeyFromASN1 returns a NEO PublicKey from the ASN.1 serialized key. func NewPublicKeyFromASN1(data []byte) (*PublicKey, error) { var ( err error pubkey interface{} ) if pubkey, err = x509.ParsePKIXPublicKey(data); err != nil { return nil, err } pk, ok := pubkey.(*ecdsa.PublicKey) if !ok { return nil, errors.New("given bytes aren't ECDSA public key") } result := PublicKey(*pk) return &result, nil } // decodeCompressedY performs decompression of Y coordinate for the given X and Y's least significant bit. // We use here a short-form Weierstrass curve (https://www.hyperelliptic.org/EFD/g1p/auto-shortw.html) // y² = x³ + ax + b. Two types of elliptic curves are supported: // 1. Secp256k1 (Koblitz curve): y² = x³ + b, // 2. Secp256r1 (Random curve): y² = x³ - 3x + b. // To decode a compressed curve point, we perform the following operation: y = sqrt(x³ + ax + b mod p) // where `p` denotes the order of the underlying curve field. func decodeCompressedY(x *big.Int, ylsb uint, curve elliptic.Curve) (*big.Int, error) { var a *big.Int switch curve.(type) { case *btcec.KoblitzCurve: a = big0 default: a = big3 } cp := curve.Params() xCubed := new(big.Int).Exp(x, big3, cp.P) aX := new(big.Int).Mul(x, a) aX.Mod(aX, cp.P) ySquared := new(big.Int).Sub(xCubed, aX) ySquared.Add(ySquared, cp.B) ySquared.Mod(ySquared, cp.P) y := new(big.Int).ModSqrt(ySquared, cp.P) if y == nil { return nil, errors.New("error computing Y for compressed point") } if y.Bit(0) != ylsb { y.Neg(y) y.Mod(y, cp.P) } return y, nil } // DecodeBytes decodes a PublicKey from the given slice of bytes. func (p *PublicKey) DecodeBytes(data []byte) error { b := io.NewBinReaderFromBuf(data) p.DecodeBinary(b) if b.Err != nil { return b.Err } if b.Len() != 0 { return errors.New("extra data") } return nil } // DecodeBinary decodes a PublicKey from the given BinReader using information // about the EC curve to decompress Y point. Secp256r1 is a default value for EC curve. func (p *PublicKey) DecodeBinary(r *io.BinReader) { var prefix uint8 var x, y *big.Int var err error prefix = uint8(r.ReadB()) if r.Err != nil { return } if p.Curve == nil { p.Curve = elliptic.P256() } curve := p.Curve curveParams := p.Params() // Infinity switch prefix { case 0x00: // noop, initialized to nil return case 0x02, 0x03: // Compressed public keys xbytes := make([]byte, coordLen) r.ReadBytes(xbytes) if r.Err != nil { return } x = new(big.Int).SetBytes(xbytes) ylsb := uint(prefix & 0x1) y, err = decodeCompressedY(x, ylsb, curve) if err != nil { r.Err = err return } case 0x04: xbytes := make([]byte, coordLen) ybytes := make([]byte, coordLen) r.ReadBytes(xbytes) r.ReadBytes(ybytes) if r.Err != nil { return } x = new(big.Int).SetBytes(xbytes) y = new(big.Int).SetBytes(ybytes) if !curve.IsOnCurve(x, y) { r.Err = errors.New("encoded point is not on the P256 curve") return } default: r.Err = fmt.Errorf("invalid prefix %d", prefix) return } if x.Cmp(curveParams.P) >= 0 || y.Cmp(curveParams.P) >= 0 { r.Err = errors.New("enccoded point is not correct (X or Y is bigger than P") return } p.X, p.Y = x, y } // EncodeBinary encodes a PublicKey to the given BinWriter. func (p *PublicKey) EncodeBinary(w *io.BinWriter) { w.WriteBytes(p.Bytes()) } // GetVerificationScript returns NEO VM bytecode with CHECKSIG command for the // public key. func (p *PublicKey) GetVerificationScript() []byte { b := p.Bytes() buf := io.NewBufBinWriter() if address.Prefix == address.NEO2Prefix { buf.WriteB(0x21) // PUSHBYTES33 buf.WriteBytes(p.Bytes()) buf.WriteB(0xAC) // CHECKSIG return buf.Bytes() } emit.CheckSig(buf.BinWriter, b) return buf.Bytes() } // GetScriptHash returns a Hash160 of verification script for the key. func (p *PublicKey) GetScriptHash() util.Uint160 { return hash.Hash160(p.GetVerificationScript()) } // Address returns a base58-encoded NEO-specific address based on the key hash. func (p *PublicKey) Address() string { return address.Uint160ToString(p.GetScriptHash()) } // Verify returns true if the signature is valid and corresponds // to the hash and public key. func (p *PublicKey) Verify(signature []byte, hash []byte) bool { if p.X == nil || p.Y == nil || len(signature) != SignatureLen { return false } rBytes := new(big.Int).SetBytes(signature[0:32]) sBytes := new(big.Int).SetBytes(signature[32:64]) return ecdsa.Verify((*ecdsa.PublicKey)(p), hash, rBytes, sBytes) } // VerifyHashable returns true if the signature is valid and corresponds // to the hash and public key. func (p *PublicKey) VerifyHashable(signature []byte, net uint32, hh hash.Hashable) bool { var digest = hash.NetSha256(net, hh) return p.Verify(signature, digest[:]) } // IsInfinity checks if the key is infinite (null, basically). func (p *PublicKey) IsInfinity() bool { return p.X == nil && p.Y == nil } // String implements the Stringer interface. func (p *PublicKey) String() string { if p.IsInfinity() { return "00" } bx := hex.EncodeToString(p.X.Bytes()) by := hex.EncodeToString(p.Y.Bytes()) return fmt.Sprintf("%s%s", bx, by) } // MarshalJSON implements the json.Marshaler interface. func (p PublicKey) MarshalJSON() ([]byte, error) { return json.Marshal(hex.EncodeToString(p.Bytes())) } // UnmarshalJSON implements the json.Unmarshaler interface. func (p *PublicKey) UnmarshalJSON(data []byte) error { l := len(data) if l < 2 || data[0] != '"' || data[l-1] != '"' { return errors.New("wrong format") } bytes := make([]byte, hex.DecodedLen(l-2)) _, err := hex.Decode(bytes, data[1:l-1]) if err != nil { return err } err = p.DecodeBytes(bytes) if err != nil { return err } return nil }